The 12 Tailed beasts (尾獣, bijū) are giant demons that serve to drive the plot of the Naruto series. They are referred to as "Chakra Monsters" because they are actually living "ultimate chakra", far beyond a normal human's and given physical form. Because of their power, the tailed beasts served as weapons and tools used in Ninja Wars until it ended and several of the tailed beasts were distributed by the First Hokage amongst the five ninja nations as a peace treaty, in order to stabilize the balance of power between nations. Each tailed beast holds unimaginable power, being seen as unfair to be kept in one place or village without fair distribution.